1. Field of the Invention
The present invention relates to a recording or reproducing apparatus for an image recording medium.
2. Description of the Related Art
A format for recording an image signal of a field on each of 50 concentric tracks formed on a magnetic disk has been agreed on by the Still Video Committee, and the agreed upon format is commonly used as the image recording medium for electronic still cameras or the like.
In electronic still cameras, in order to avoid double recording of the image signal, the recorded/unrecorded states of the tracks of the magnetic disk are searched in advance, and the result of the search is stored as a table in an internal memory and is referred to at the subsequent recording or reproduction. Also, in order to enable immediate recording of the image on the magnetic disk, at the start of power supply or at the loading of the magnetic disk, the presence or absence of a RF reproduction signal is detected in succession from the innermost 50th track toward the outer tracks, and the magnetic head waits on a track immediately inside the first recorded track found.
In the still video floppy disk, the empty tracks may be present in a scattered manner, because the recorded image may have been erased. Consequently, empty tracks may be present outside the empty track on which the magnetic head was positioned by the search operation at the loading of the magnetic disk. Conventionally, in the table indicating the recorded/unrecorded state of each track (hereinafter called track table), each track is given a 2-bit flag, which is set as "11" for a confirmed recorded track, "01" for a confirmed unrecorded track, or "00" for an unconfirmed track.
Thus, at the loading of the magnetic disk or immediately after the start of power supply, the flags of said track table are initialized to "00". In the initial positioning operation of the magnetic head, the first recorded track found in the search from the inside is given a flag "11", while the inner tracks are given flags "01", and the outer tracks are given "00" because they have not yet been searched.
In the interval reproduction mode in which the recorded tracks only are reproduced in succession at a predetermined interval, access is not made to the tracks having a flag "01" in the track table, but is made to the tracks having "00" to check the recorded/unrecorded state by the RF reproduction signal. If the track is recorded, the recorded signal is reproduced and the corresponding flag is changed to "11". If the track is unrecorded, reproduction is not conducted and the flag is changed to "01". The recorded tracks are reproduced in succession in this manner by checking of the recorded/unrecorded state.
However, in such a conventional structure using 2 bits for each track, a memory area as large as 100 bits is required for 50 tracks. Such a memory area is often formed in a RAM integrated in a one-chip microcomputer, but such track information should preferably be as small as possible, because the entire memory capacity is limited.
Also in a electronic still camera with a conventional reproducing function, the outer-most track of the still video floppy disk is reproduced automatically when the operating mode is switched from recording to reproduction.
In such a structure, however, in case of observing the recorded image immediately after the image has been recorded on the floppy disk in the recording mode, cumbersome operations are required including first switching the recording mode to the reproduction mode thereby setting the magnetic head on the first track, and then returning the magnetic head to the track recorded immediately before by means of manual manipulation of up- and down-switches.